A variety of peripheral components are coupled to electronic devices, such as computers. For example, many computers now comprise at least one universal serial bus (USB) port through which peripheral devices may be connected to the computer. For example, USB cables can be used to connect printers, scanners, mice, joysticks, web cams, modems, speakers, telephones and many other devices to an electronic device for interaction with the device. The USB port is an input/output port that may be coupled to a USB cable having two wires for power (+5 volts and ground) and a twisted pair of wires for carrying data. Based on the USB standard, 0.5 amps are available at five volts (2.5 watts) at the USB port. Thus, the USB standard enables the powering of a variety of low-power devices directly through device USB ports.
However, for high-power devices, such as mass storage devices, insufficient power is available at a USB port constructed according to the basic requirements of the USB specification. Accordingly, such devices are powered by an external power supply. If such a high-power device is not powered by an external power supply and is coupled to a USB port having insufficient power available, detrimental results can occur. For example, the peripheral device may not function properly, or the power draw of the peripheral device can trigger an automatic shut down of the USB port or overall electrical device.